Mushrooms have been in the kashrus news recently, as
canned mushrooms produced in China, which are very common in
Israel, were found to have bugs that were not previously
detected. In the wake of this discovery, Rav Moshe Vaye
investigated the issue and wrote this report of his
findings.

A Survey of the History of Mushrooms

From various halochos explained in Shas it
seems that in the times of Chazal mushrooms were already a
popular delicacy:

In the gemora (Brochos 40a) we learn that the
brochoh on mushrooms is shehakol because they
grow from the air, not from the ground.

In Brochos (47a) Rashi explains that the amora
Shmuel liked to eat mushrooms at the end of the meal.

Also in maseches Kesuvos (61a) it mentions
"tavshila de'ardi" (see Rashi there), and in
Nedorim (25b), "He who vows to abstain from fruit of
the earth may not eat any fruit (vegetables), but may eat
mushrooms."

The Yerushalmi in Ma'asros (1:1) explains that
mushrooms are exempt from terumos and ma'asros
because they are not planted from seeds.

As far as the laws of shmittah, the Meiri (Avoda
Zora 14) says that mushrooms do not have kedushas
Shevi'is since they do not grow from roots.

Infestation in Mushrooms

Although as far as the laws of brochos are concerned
mushrooms are not considered to nourish from the ground, when
it comes to the prohibition of insects, the Ramo (Yore
Dei'ah 84:6) explains that they are considered attached
to the ground: "Insects that grow in mushrooms have the same
status as those in other vegetables and we do not say that
they are not considered attached to the ground since we do
not make a "borei pri ho'adomoh" on them."

The Taz explains that they are called attached to the ground
and the insects are considered to have swarmed on the ground.
(This is in contrast to the opinion of the Issur Veheter
brought in Darchei Moshe who considers mushrooms as
separate from the ground as far as insects as well.) See also
in Biur HaGra (loc. cit. 19).

We find another reference to infestation in mushrooms in the
Maharshal (Yam Shel Shlomo, Chapter Eilu Treifos) who
writes that he avoided eating dried mushrooms because they
are muchzak betolo'im. The Pri Chodosh (84:19) quotes
him and adds that they should also not be eaten because of
the danger since many wild mushrooms are poisonous. He says
that they used to feed them to cats before eating them, and
some of the cats died or became insane.

The Darchei Teshuva brings down from the Shulchan Govohoh
that they ate mushrooms, but that the dried ones were very
infested and they used to eat them only after careful
inspection, by breaking them into pieces and checking for
small holes inside them, which is a sign of infestation.

The Pri Megodim (84, Sifsei Daas siman koton 33)
discusses using mushrooms by filtering, "As far as dried
mushrooms, which are definitely infested, we have to look
into whether it is permitted to wrap them in a linen cloth
and place them in a pot of food to sweeten the food. And this
is not considered being mevatel issur lechatchiloh,
since his intention is only to use the juice of the
mushrooms. It would seem that it is forbidden to do so, but
one should not reprimand someone who does so using a very
thick cloth through whose holes the insects cannot pass."

In another place (Orach Chaim 453 in Eshel Avrohom
siman koton 3) he writes that with dried mushrooms using
this method it is permissible to eat the juice even if the
mushrooms are wormy, but he should still first remove
whatever insects he can.

In Chochmas Odom (38:18) he writes that mushrooms are
muchzak betolo'im, and this is also brought in
Metzudas Zion on Kitzur Shulchan Oruch (46:39) and in
the sefer Shimusho Shel Torah.

Mushroom Growing

In nature, there are about 2,000 species of wild mushrooms
that are fit for human consumption, in addition to many
species of poisonous mushrooms, most of which are lethal.

In olden times mushrooms were eaten, but there was no way to
grow them commercially since they do not have seeds.

Three hundred fifty years ago, the French succeeded in
growing mushrooms in caves around Paris (where they still
grow mushrooms today), but it was only about 100 years ago
that a commercially viable method of growing mushrooms was
devised by sprouting mushroom spores. About 10 years later,
in the U.S., a building in which mushrooms could be grown was
developed, turning mushroom-growing into a commercial
agricultural endeavor.

At that time mushrooms were grown only in cool climates, such
as Western Europe and several American states. Fifty years
ago, they began to be grown in the Far East during the cold
season, and for the past 30 years they have been grown in
climate-controlled buildings in which they can grow all year
round.

Only 10 different varieties of cultivated mushrooms are grown
throughout the world, and the worldwide production totals
over a million tons a year.

In Israel, a limited amount of fresh mushrooms are grown but
the bulk of the mushrooms consumed here are imported, canned
mushrooms. Until 20 years ago, the bulk of the imports were
from Holland. However, with the development of the mushroom
industry in China, the center for imports switched to China,
since mushroom- processing requires cheap manual labor, which
is in abundant supply in China.

Consumption in Israel has grown considerably over the past
years, and today 50 million cans a year(!) are imported,
mainly from China, with some coming from Holland, France, and
Poland. This is an amount that is about the same as that
imported to Germany, which has more than 13 times the
population of Israel.

Mushroom Infestation

Mushrooms are prone to many forms of infestation, especially
fly maggots and mites. (Maggots are tiny worms that develop
into flies). The main pests are:

1. Maggots of the sciarid fly. These are white with a
black head, and range in length from 4 to 8 mm. The fly lays
her eggs inside the compost used to nourish the mushrooms,
from which the maggots hatch and enter the mushrooms. They
burrow tunnels inside the mushroom stem and cap.

2. Maggots of the phorid fly (MEGASELIA). These
flies are attracted to the odor of the growing medium from a
distance of many kilometers! Each female lays about 50 eggs
in the compost, from which white maggots hatch. The maggots
penetrate the mushrooms, making holes in the mushroom.

3. Larvae of the cecid fly (MYCOPHILA). These
are very tiny flies, 2 mm. long. The maggot is 2- 3 mm. long.
They are very prolific, and in an untended bed there may be 4
1/2 million larvae in a square meter.

4. Mites. The mushrooms may harbor mites, which look
like white or brown grains of sand crawling around on the
mushroom. They produce stains and holes in the mushroom.

Mushrooms that grow wild are liable to be extremely infested,
and so Jews were always scrupulous to eat them only after
meticulous inspection (see Section B above).

For example, in Mexico there is a type of mushroom that is
considered a delicacy, which is picked in forests but it is
very infested.

In developed countries, cultivated mushrooms are grown under
special conditions to prevent insect infestation. On the
other hand, mushrooms that are not tended may be very heavily
infested.

Preventing Infestation

To prevent infestation, mushroom-growers grow them under
special conditions.

Modern mushroom-growing takes place in dark growing halls
which are completely sealed, with all the air filtered
through fine filters. The halls are climate- controlled, and
are equipped with heating, cooling, steam, ventilation, and
circulation equipment. Inside the building, long iron shelves
called "beds" are arrayed. The growing medium is spread on
the shelves. It consists of compost containing wheat chaff,
rice chaff, and organic fertilizer, to which vegetable matter
is added. A layer of earth is spread over this. The compost
is pasteurized to kill any living organisms such as bacteria,
mites, and the eggs of various flies and larvae which attack
mushrooms. In addition, the buildings have exterminations
periodically. Entry to the building is permitted only to
those wearing special clothing, to prevent insects from
reaching the mushrooms. The mushrooms grow evenly and are
harvested by automatic robot machines.

Cultivated mushrooms, grown in good, modern conditions such
as described above, are usually free of insects. In case of
neglect or mishap, the mushrooms may become infested. For
this reason, in my sefer, Bedikas Hamozon Cahalocho Part
I, I recommended checking the mushrooms. With good-
quality mushrooms, it is enough to check a sample.

Fresh mushrooms grown in Israel have been found to be clean
of infestation, and may be eaten after checking a
sampling.

Mushroom-Growing in China

Although the Chinese have been growing mushrooms only for the
past 20 years, the methods used are primitive, and against
all accepted modern procedures that we described above. Each
farmer builds his own improvised growing hut in his yard.

The huts are built either from stone or bamboo, over which
black plastic sheets and tree branches are spread. The huts
are more open than closed, and flies and other pests that
attack mushrooms can enter without any difficulty. Even the
stone buildings that are used have many openings with plastic
curtains that do not seal the openings, as well as an open
entry way.

The growing medium is not properly sterilized, and in most
places no professional extermination is done. The huts are
located in swampy areas, and the puddles of water provide an
excellent breeding ground for flies.

The farmer harvests the mushrooms by hand at dawn when the
weather is cool, loads them onto his wagon or motorcycle, and
quickly takes them to the plant (the texture of the mushroom
is delicate and changes quickly), where they are immediately
processed by boiling. The plant receives mushrooms from
hundreds of growers, and it is impossible to control the
quality of the sources.

Therefore in almost every can from China there are some
infested mushrooms. For example, out of a six-can sample that
was checked, infestation was found in five of the cans. In
another case, 8 cans out of 9 were found to harbor
infestation. Only some of the mushrooms in the can are wormy,
generally 3-5 mushrooms out of the 15-25 mushrooms in the
can. Insects were found in both whole and cut mushrooms.

The maggots are hard to identify, because they are found
underneath the thin skin that connects the stem to the cap,
or inside the flesh of the mushroom. The maggots are tiny --
1-3 mm. long -- and identical in color to the mushroom
itself. Identifying them requires expertise and sharp
eyes.

Unlike the infestation in wild mushrooms, these maggots do
not make holes in the mushroom and the mushroom seems
superficially to be of superior quality. Because of the
maggots' tiny size and their being hidden under the peel,
this infestation was not discovered in the past, although
apparently it has existed for many years. (We found
infestation in cans that were several years old.)

The conclusion is that, without radical changes in the
methods of growing mushrooms in China, there is no
possibility of producing clean mushrooms there. It will be
possible to try to do so only if the openings of the solid
buildings are sealed with fine mesh, the growing medium is
effectively sterilized and the buildings are also disinfected
(insects and mites live inside the bamboo frames), and the
beds are professionally exterminated.

The entire growing and production process must be supervised
by experienced mashgichim who make sure that the
buildings are sealed, check samples of mushrooms from the
buildings, ensure that the packing plants use produce only
from certified stone buildings, and check large samples of
the finished product during the entire production season, as
well as laboratory tests of the finished product which
confirm that it is completely insect-free.

Mushrooms in Other Countries

In conjunction with the investigation of mushrooms from
China, mushrooms imported from other countries were also
checked. Surprisingly, in mushrooms originating from
countries using modern methods, a high rate of infestation
was also found!

For example, infestation was found in whole mushrooms from
Holland; a very high rate of infestation was found in frozen
and canned mushrooms from France. Mushrooms from Spain and
other countries were also found to harbor infestation.

Mashgichim who went to Holland then discovered that in
Holland, only cut mushrooms are generally produced. Whole
mushrooms, which require intensive manual labor, are imported
from China (!), canned in Holland and reexported.

Conclusions

The can or container should be marked as having been produced
under special supervision, and that the mushrooms are insect-
free.

These conditions also apply to frozen and dehydrated
mushrooms. Dehydrated mushrooms should be stored in airtight
containers or in a vacuum, to prevent new infestation from
developing during prolonged storage.

Halachic Questions

1. Q. Can we consider the surfaces on which the medium
is laid as a vessel with the halachic status of a "flowerpot
without a hole" (otzitz she'eino nokuv)? If so, could
the worms in the mushrooms be considered a worm that was born
in something detached from the ground and never went out,
which is not ossur? (See Yoreh Dei'ah 84:4).

A. In my sefer Bedikas Hamozon Cahalocho (Note
6 in Chapter 3), I write about a similar question that was
brought before Rav Shlomo Z. Auerbach zt"l concerning
vegetables grown in a flowerpot without a hole. He was asked
about the status of a worm that hatched inside the flesh of a
leaf growing in the flowerpot and never went out, and he
answered that it requires further clarification and we would
have to find a precedent (ra'aya) to permit it.

In Darchei Teshuva (84:82) he quotes both the Minchas
Yitzchok, who is undecided as to whether insects in mushrooms
that grow inside vessels are considered as "crawling on the
ground," and the Orach Mishor, who says that the mushrooms
are definitely considered attached to the ground, making the
worms prohibited.

However, in fact the above questions are irrelevant, since
the growing surfaces in which the mushrooms are grown
everywhere are like nets. In Europe the nets are made of
metal, and in China they are just strips of bamboo holding up
the medium. The floors of the huts in China are earth, not
concrete, so that the medium cannot be considered a flowerpot
without a hole. In addition, the flies lay their eggs in the
medium itself, where the maggots develop, move around, and
then go into the mushrooms, so that they cannot be said to
have hatched inside the mushroom.

2. Q. Since infestation was found in the majority of
the cans, both whole and cut, and canned mushrooms should not
be used, what is the halochoh bedi'eved, for example a
food that was cooked with mushrooms that were not checked?
Can the mushrooms be removed and the food eaten?

A. In my sefer Bedikas Hamozon Cahalocho, page
182 question 4, I asked HaRav Shlomo Z. Auerbach zt"l
a similar question and he answered that we do not hold
that the insects are transferred (ein machzikim mimokom
lemokom), and the food is permitted. And the gedolei
haposkim today also paskened the same way
regarding mushrooms.

If it is not possible to remove the mushrooms, there is a
possibility of leniency bedi'eved and one may eat the
food.

Infestation was also found in dehydrated mushrooms which are
used in manufacturing soup mix. If the soup has whole or
sliced mushrooms, the mushrooms should be removed. Soup with
finely ground mushrooms may be eaten. With soup with small
pieces of mushroom, it is desirable to grind the soup well.
This is the opinion of the gedolei haposkim as
well.

3. Q. May a manufacturer store dehydrated mushrooms
for 12 months, after which the insects are like dust? (See my
sefer Bedikas Hamozon Cahalocho chapter 9 of the
halocho section). Usually during prolonged storage, new
insects develop in the food (ibid. chapter 5 paragraph
8). Therefore, one of the kashrus organizations suggested
storing the mushrooms in an air-conditioned warehouse to
prevent new infestation. Is air-conditioning like freezing,
which preserves the worms in their current state (see HaRav
S. Z. . Auerbach's teshuva there, question 7), or is
air-conditioning like winter conditions? Nowhere do we find
that in winter conditions or in a cold country the din
of 12 months does not apply.

A. The gedolei haposkim answered that it
depends on what actually happens, and we should follow up
what happens during storage: whether the worms dry up and
turn into dust, and whether the mushrooms remain free of new
infestation.

4. Q. If someone has a large supply of infested
mushrooms, may he give them or sell them to a non-Jew, or
must he be concerned that the non-Jew will sell them to a
Jew? (See Bedikas Hamozon Cahalocho Chapter 10
paragraph 3 in the halocho section).

A. The gedolei haposkim answered that here in
Israel, where it was widely publicized that the mushrooms are
infested, one need not worry that they will be sold to a Jew,
and one may sell them to a non- Jew.

5. Q. Whereas a mashgiach can check at most 30 -
40 cans a day, and a day's production comprises tens of
thousands of cans, can we rely on this as a representative
sample, since it is only a very small percentage of the
total? On the other hand, when the mushrooms were infested we
found infestation in 4 out of 5 cans, and even in cleaner
specimens, infestation was found in 2 out of 10 cans, so that
a sample of 30 - 40 cans can give a reliable picture of the
situation.

A. The gedolei haposkim answered that in a case
like this, we can rely on a sample of this size.

Procedure for Checking FRESH Mushrooms

1. Try to use only fresh, firm, nice-looking mushrooms.

2. Wash the mushrooms well to remove the remnants of the
growing medium (dark crumbs). Remove any dark spot or mushy
area.

3. Separate the cap from the stem and examine the resulting
hollow area in the cap, as well as the upper surface of the
stem, checking for small "pinprick" holes. In addition, one
should look for small white worms on the upper part of the
stem.

4. Examine the brown gills (made up of thin brown lines) on
the underside of the cap, to see whether the area is mushy,
or if there are small white or red mites.

5. Break the cap into several pieces (3-4) or slice it. Do
the same to the stem. Check for small holes or mites.

If holes are found, do not use that mushroom and check the
rest of the mushrooms well. If mites are found, do not use
any of the mushrooms from that package.

With high-quality mushrooms, one can rely on checking a
sampling of the mushrooms. If infestation is found in the
sampling, the entire batch must be checked.